Recent advances in autologous bone marrow transplant strategies indicate that normal hematopoiesis can be promptly restored in patients treated with myelotoxic agents (drugs or radiation) by re-injection of autologous peripheral blood (CD34.sup.+) "stem cells" (Gianni, et al., Lancet 2:580, 1989). In addition, it has very recently been reported that CD34.sup.+ cells can be transduced in vitro at high efficiency with retroviral vectors expressing specific genes (Bregni, et al., Blood 80:1418, 1992). These technologies open the way to approaches in which the in vitro transduction of specific genes into autologous CD34.sup.+ cells followed by reinoculation into patients can be used to transduce genes of therapeutic significance. This gene therapy approach includes the reconstitution of drug-resistant hematopoietic cells allowing for subsequent treatment with higher dose myelotoxic chemotherapy in cancer patients.